The genetic position of the lex-114 mutation and ssbA-1 mutations on the Escherichia coli chromosome has been found to be very close to the mutation lexC-113. Two-dimensional electrophoretic studies of all three mutant strains demonstrate a similar, but not identical, pattern of protein synthesis in response to growth in presence of nalidixic acid. The lexC-113, lex-114, and ssbA-1 strains, however, differ distinctly from the lexA and recA mutant strains.